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2018 Pea Leaf Weevil Survey

 
 
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.Note that this is not a forecast, it is a survey of the situation in the Spring of 2018.

The annual pea leaf weevil (Sitona lineatus L.) survey was carried out in late May and early June, 2018. Evidence of feeding in 2018 once again was over a wider range than in previous years. The range of pea leaf weevil activity has expanded dramatically in central Alberta since 2013.

The 2018 survey is based on damage ratings in 203 fields from 46 municipalities.

Survey locations shown with black circles had no evidence of pea leaf weevil feeding on any of the plants assessed.

For a PDF version of the map

In each field the total notches per plant are counted on 50 plants (10 plants in 5 locations near the field margin). The damage rating for a particular field is the average number of notches per plant. It is important to note that although this survey concentrates on adult damage, yield losses are caused by the larval damage to the nitrogen fixing root nodules. Information about the pea leaf weevil and its life cycle can be found here.

The level of pea leaf weevil feeding damage was the lowest observed in the past eight years. The highest damage ratings were along Highway 2 and southern Alberta with reduction in adult damage by pea leaf weevil in eastern Alberta. Pea leaf weevil is now established from southern Alberta through west-central Alberta as far as Barrhead County northwest of Edmonton. The survey also shows that pea leaf weevil is now found in several counties in the Peace River region. Feeding damage in the spring of 2018 remains low in the Peace but reports of high numbers of adults in August may indicate a change to that situation.

While this is not a strict forecast, experience has shown us that activity levels greater than 9 notches per plant is sufficient to cause significant damage if conditions are favorable in the spring of 2019. This covers a large area of southern and west central Alberta. For any producers south of Highway 9 and along Highway 2 up to Edmonton there is a risk of damaging levels of pea leaf weevil in 2019. Producers should use this information along with their own experience to plan control strategies such as seed treatment for the 2019 crop year. Research has shown that seed treatment is much more effective in reducing losses from pea leaf weevil than foliar treatments.

In addition, since 2014 significant pea leaf weevil damage has been seen on fababeans in a much larger area than shown in this survey that is conducted on field peas. This insect causes as much or more damage on fababeans. The true economic damage of this insect on both peas and fababeans on the higher organic matter soils of central Alberta is not well understood but research has been initiated to work out these relationships.

Spring weather conditions have a very large impact on the timing and severity of pea leaf weevil damage. When warm conditions (>20 C) persist for more than a few days in late April or early May the weevils arrive in fields early. Early arrival corresponds to the potential for higher yield losses. In years where cool weather persists, the arrival of PLW can be much later and the resulting yield impact is lower especially when the crop advances past the 6 node stage before weevils arrive. In every case control decisions should be made on a field by field basis.

Spring weather conditions have a very large impact on the timing and severity of pea leaf weevil damage. When warm conditions (>20 C) persist for more than a few days in late April or early May the weevils arrive in fields early. Early arrival corresponds to the potential for higher yield losses. In years where cool weather persists, the arrival of PLW can be much later and the resulting yield impact appears to be lower especially when the crop advances past the 6 node stage before weevils arrive. In every case control decisions should be made on a field by field basis.

Life cycle information

Frequently Asked Questions

Historical pea leaf weevil survey maps from 2008-2017.

Feeding damage on faba bean
Shelley Barkley, Alberta Agriculture and Forestry
Pea leaf weevil
Shelley Barkley, Alberta Agriculture and Forestry

Feeding damage on seedling alfalfa
Shelley Barkley, Alberta Agriculture and Forestry
The 2018 pea leaf weevil survey was carried out by Alberta Agriculture and Forestry staff.

Thank you David Giffen, Agriculture and Agri-Food Canada, Saskatoon for building the map.

Thank you Jan Lepp, Alberta Agriculture and Forestry for managing the data from this survey.

For more information on this insect and its management contact the Ag-Info Centre at 310-FARM (3276) or email bugs.r.us@gov.ab.ca


 
 
 
 
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For more information about the content of this document, contact Scott Meers.
This document is maintained by Shelley Barkley.
This information published to the web on December 5, 2018.